Every computer concept has peripheral devices for the input and output (I/O) of data, commands and programs
. Since the two processes, input and output, are essentially different from each other, processors work with special control procedures
, etc. Control procedures include polling, in which the processor queries the registers at certain intervals about the status of the peripherals, and handshaking for consensual data transfer. Furthermore, XON/XOFF should be mentioned, daisy chaining and interrupt control.